This invention relates to sewing machine lubrication and more particularly to a lubrication system controlling the flow of lubricant to the operating mechanism during the operation of the machine and for terminating the flow of lubricant when the machine is stopped.
For some time the sewing machine industry has been concerned with the problem of lubricating the moving parts of high speed machines with a system for delivering a predetermined quantity of lubricant during operation and for terminating the flow of lubricant when the sewing machine is stopped. It is known in these high speed machines to utilize a wicking for feeding lubricant from a reservoir to the moving parts of the machine. In many of the prior art sewing machines a wicking was disposed within the lubricant and through capillary action lubricant was fed to the moving part. However, this arrangement was found unsatisfactory since oil was continuously fed through the absorption process and capillary action from the reservoir to the moving parts in the head of the machine even while the machine was inoperative. Thus, if a machine was allowed to sit inoperative for a period of time the reservoir would be drained dry and the oil pan in the bed of the machine would overflow with oil.
In an attempt to overcome these disadvantages the prior art developed a number of proposals by which the wick was wetted by a positive action through a plunger or a vibratory spring member which brought the wick into contact with the oil. Systems of this type are illustrated in Parry et al., U.S. Pat. No. 2,771,965 and Ross, U.S. Pat. No. 3,011,592. Another proposal in which the wick is wetted through capillary action but which requires a manual action through a plunger mechanism to cause oil to flow into a tube wherein capillary action will cause the wick to be wetted is illustrated in Japanese Utility Model Registration No. 481,381 dated Aug. 23, 1958.